Inductively coupled plasma reactor for producing nano-powder

ABSTRACT

Disclosed herein is a high-frequency induction plasma reactor apparatus for producing nano-powder, which is configured to continuously manufacture nano-powder in large quantities using solid-phase powder as a starting raw material and to manufacture high-purity nano-powder by completely vaporizing the material powder. The high-frequency induction plasma reactor apparatus comprises an upper body and a cover. The upper body is provided with a reaction pipe receiving a reactor extending vertically inside thereof, a high-frequency coil surrounding the outer periphery of the reaction pipe and a ceramic inner wall provided inside the reaction pipe. The ceramic inner wall is formed with a plurality of gas passing bores and defines a gas movement passage with the inner side wall of the reaction pipe therebetween for allowing the inflow of argon gas from the outside into the reactor. The cover is mounted to the upper end of the reactor and adapted to seal the reactor. The cover is provided with a powder injection tube communicating with the reactor.

TECHNICAL FIELD

The present invention relates generally to a plasma reactor apparatusfor producing nano-powder at atmospheric pressure using high-frequencycoils. More specifically, the present invention relates to ahigh-frequency induction plasma reactor apparatus for producingnano-powder, which is configured to continuously manufacture nano-powderin large quantities using solid-phase powder as a starting raw materialand to manufacture high-purity nano-powder by completely vaporizing theraw material powder.

BACKGROUND ART

Generally, a nano-powder producing reactor is referred to an apparatusfor manufacturing nano-powder by vaporizing gas-phase or liquid-phasematerials as raw materials. The nano-powder manufactured using thereactor is input into and collected in a separate collecting device.

A conventional reactor produces nano-powder by implementing ionizationand dissociation of reactants, using plasma torches of direct-currenttype, high-frequency type, direct-current/high-frequency type and so on.Specifically, the reactor attains nano-powder by generating plasma arccolumns between electrodes of the plasma torches and maintaining theplasma arc columns continuously.

In the conventional reactor, however, several problems may beencountered while using it. One recurring problem is that theconventional reactor is configured to use only gas-phase or liquid-phasematerial as a starting raw material and thus solid-phase material is notallowed in the manufacture of nano-powder. This makes the continuousmass production of nano-powder impossible.

Another shortcoming of the conventional reactor is a limitation ofapplicable materials. In the conventional reactor, because of explosivereaction and powder adsorption problems caused by water vapor containedin the reactor, only non-reactive oxide based materials (for example,alumina and so on) are acceptable.

Further, the conventional reactor is unable to control plasma becausethe reactor has no separate plasma control device.

Finally, the moisture content percentage within the conventional reactoris insufficient. This is fundamentally attributable to a low spaceutility of the reactor. In the case of the conventional reactor, only aspace between the electrodes of plasma torches, instead of the overallspace of the reactor, is usable.

DISCLOSURE OF THE INVENTION

Therefore, the present invention has been made in view of the aboveproblems, and it is an object of the present invention to provide ahigh-frequency induction plasma reactor apparatus for producingnano-powder, which is configured to manufacture high-purity nano-powderby vaporizing solid-phase material powder, using high-frequencyinduction heat at atmospheric pressure.

It is another object of the present invention to provide ahigh-frequency induction plasma reactor apparatus having upper and lowerreactors arranged in two stages, the lower reactor having a temperatureand capacity larger than those of the upper reactor, thereby enablingthe complete vaporization of material powder.

It is further another object of the present invention to provide ahigh-frequency induction plasma reactor apparatus, which is configuredto prevent the growth and adsorption of vaporized nano-powder via theinflow of cryogenic coolant (i.e. argon gas) into the reactor.

It is another object of the present invention to provide ahigh-frequency induction plasma reactor apparatus, which is configuredto helically guide coolant gas into the reactor, thereby safely movingmolten and vaporized nano-powder to a collecting station via the helicalmotion thereof without agglomeration.

It is yet another object of the present invention to provide ahigh-frequency induction plasma reactor apparatus, which is configuredto prevent plasma from being adsorbed to the inner wall of the reactor,using permanent magnets mounted around the periphery of the reactor.

In accordance with the present invention, the above and other objectscan be accomplished by the provision of a plasma reactor apparatus forproducing nano-powder comprising: an upper body having a reaction pipereceiving a reactor extending vertically inside thereof, ahigh-frequency coil surrounding the outer periphery of the reactionpipe, and a ceramic inner wall provided inside the reaction pipe, theceramic inner wall being formed with a plurality of gas passing boresand defining gas movement passage with the reaction pipe there betweenfor allowing the inflow of argon gas from the outside into the reactor;and a cover mounted to an upper end of the reactor and adapted to sealthe reactor, the cover being provided with a powder injection tubecommunicating with the reactor; wherein the upper body is provided witha permanent magnet assembly around the periphery of the high-frequencycoil, the magnet assembly comprising a plurality of permanent magnetsuniformly combined by fixing means and having inner ends of the samepolarity as one another so that they compress plasma inside the reactor,thereby preventing the plasma from being adsorbed to the wall of thereactor.

Preferably, the plasma reactor apparatus for producing nano-powder mayfurther comprise a lower body mounted under the upper body, the lowerbody having a reaction pipe receiving a reactor communicating with thereactor of the upper body, a high-frequency coil surrounding the outerperiphery of the reaction pipe, and a ceramic inner wall provided insidethe reaction pipe, the reactor of the lower body having a diameterlarger than that of the reactor of the upper body, the high frequencycoil of the lower body having a capacity larger than that of the highfrequency coil of the upper body, the ceramic inner wall being formedwith a plurality of gas passing bores and defining a gas movementpassage with the reaction pipe therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a sectional view illustrating a plasma reactor apparatus inaccordance with the present invention;

FIG. 2 is a cross sectional view taken along the line A-A of FIG. 1;

FIG. 3 is perspective view illustrating a ceramic inner wall inaccordance with the present invention; and

FIG. 4 is a perspective view illustrating permanent magnets inaccordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a sectional view illustrating a plasma reactor apparatus inaccordance with the present invention, and FIG. 2 is a cross sectionalview taken along the line A-A of FIG. 1. First, the configuration of aplasma reactor apparatus will be described.

Referring to FIGS. 1 and 2, a plasma reactor apparatus of the presentinvention comprises an upper body 1, a cover 2, and a lower body 3. Theupper body 1 is provided with a reaction pipe 11 receiving a reactor 111extending vertically inside thereof, and a high-frequency coil 12surrounding the outer periphery of the reaction pipe 11. The cover 2 ismounted to the upper end of the reactor 111 and adapted to seal thereactor 111. The cover 2 has a powder injection tube 21 communicatingwith the reactor 111 to inject material powder into the reactor 111.

The lower body 3, located under the upper body 2, is provided with areaction pipe 31 receiving a reactor 311 extending vertically insidethereof, and a high-frequency coil 32 surrounding the outer periphery ofthe reaction pipe 31. The reactor 311 of the lower body 3 has a diameterlarger than that of the reactor 111 of the upper body 1, and thehigh-frequency coil 32 of the lower body 3 has a capacity greater thanthat of the high-frequency coil 12 of the upper body 1. Thus, the lowerbody 3 is adapted to completely vaporize the material powder havingpassed by the reactor 111 of the upper body 1.

The respective upper and lower bodies 1 and 3 are provided with ceramicinner walls 13 and 33, respectively. The respective ceramic inner walls13 and 33 are formed with a plurality of gas passing bores 132 and 332,respectively, and define gas movement passages 131 and 331 with therespective reaction pipes 11 and 31, respectively.

The respective reaction pipes 11 and 31 of the upper body 1 and lowerbody 3 have ceramic inner and outer side walls 112 and 113, and 312 and313, respectively. The reaction pipes 11 and 31 are adapted to receivewater from the outside and circulate the water therein, thereby coolingthe inner side walls 112 and 312 thereof.

The cover 2 is provided with a gas inflow canal 211 for allowing theinflow of argon gas from the outside. The gas inflow canals 211communicates with the powder injection tube 21. The cover 2 is alsoprovided therein with a cooling tube 212 arranged adjacent to the lowersurface of the cover 2. The cooling tube 212 is adapted to receivecooling water from the outside. The cooling water is used to cool thelower surface of the cover 2.

The upper body 1 and lower body 3 are provided with insulators 4 betweentheir adjacent connecting ends facing each other. The insulators 4 serveto prevent the conduction of heat toward the upper and lower bodies 1and 3.

In addition, the upper body 1 and lower body 3 are provided with aplurality of insulating bars 5 arranged uniformly around their outerperipheries, respectively. The insulating bars 5 serve to protect thereaction pipes 11 and 31 and high-frequency coils 12 and 32.

Now, the operation of the plasma reactor apparatus will be described inreference to FIGS. 1 and 2.

When electric power is supplied to the respective high-frequency coils12 and 32 of the upper body 1 and lower body 3, due to high frequenciesemitted from the respective high-frequency coils 12 and 32, thetemperatures of the respective reactors 111 and 311 of the upper body 1and lower body 3 are raised. In this case, since the high-frequency coil32 of the lower body 3 has a capacity larger than that of thehigh-frequency coil 12 of the upper body 1, the reactor 311 of the lowerbody 3 is adapted to maintain a high temperature relative to the reactor111 of the upper body 1.

Then, the material powder having a large particle size is input into thereactor 111 formed inside the reaction pipe 11 of the upper body 1through the powder injection tube 21 formed to penetrate the centralvertical axis of the cover 2.

The input material powder inside the reactor 111 of the upper body 1 ismelted and vaporized due to the high temperature of the reactor 111.According to this vaporization of the material powder, gas containingnano-powder is obtained.

Upon completion of vaporization in the reactor 111 of the upper body 1,however, a part of the gas is not vaporized completely, and remains in amolten state. This molten material falls into the reactor 311 of thelower body 3, and then is re-heated and vaporized in the reactor 311.

Since the reactor 311 of the lower body 3 has a higher temperature thanthe reactor 111 of the upper body 1, the non-vaporized molten materialhaving passed through the reactor 111 of the upper body can be vaporizedcompletely in the reactor 311 of the lower body 3.

Hereinafter, details of the present invention will be explained.

As shown in FIGS. 1 to 3, the respective ceramic inner walls 13 and 33are formed with a plurality of gas passing bores 132 and 332,respectively, and define the respective gas movement passages 131 and331 with the respective inner side walls 112 and 312 of the reactionpipes 11 and 31.

The gas passing bores 132 and 332 extend diagonally through the innerwalls 13 and 33 so that their outlets are inclined laterally anddownwardly relative to their inlets. Because of this diagonalorientation of the gas passing bores 132 and 332, the inflow outsidegas, namely, the argon gas, creates a helical eddy current within thereactors 111 and 311.

The argon gas first is supplied from the outside into the gas movementpassages 131 and 331 and then injected through the gas passing bores 132and 332 of the inner walls 13 and 33 into the reactors 111 and 311 whileforming a helical eddy current.

The molten and vaporized powder passes successively through the reactor111 of the upper body 1 and the reactor 311 of the lower body 3 whileforming a helical eddy current, and then falls into a collecting device.

The swirling movement of the powder prevents the agglomeration andadsorption of the powder to the inner wall of the reactor during itsdownward movement.

As shown FIGS. 2 and 4, the respective upper and lower bodies 1 and 3are provided with respective permanent magnet assemblies 14 and 34around the peripheries of the high-frequency coils 12 and 32. Therespective magnet assemblies 14 and 34 comprise a plurality of permanentmagents 141 and 341 fixed with fixing means while being uniformly spacedfrom one another. The permanent magnets 141 and 341, having inner endsof the same polarity as one another, are adapted to compress the plasmainside the reactors 111 and 311, thereby preventing the plasma frombeing adsorbed to the inner walls of the reactors 111 and 311.

INDUSTRIAL APPLICABILITY

As apparent from the above description, the present invention provides ahigh-frequency induction plasma reactor apparatus which is configured toenable the continuous mass production of nano-powder using solid-phasepowder as a starting material.

According to the present invention, the high-frequency induction plasmareactor apparatus can manufacture high-purity nano-powder by completelyvaporizing material powder supplied into the reactor.

Since the growth and adsorption of vaporized nano-powder is preventedusing cryogenic coolant gas (i.e. argon gas) flown into the reactor,certain strongly reactive materials are also applicable.

The high-frequency induction plasma reactor apparatus is configured tohelically guide the coolant gas into the reactor, thereby safely movingmolten and vaporized nano-powder to a collecting station via the helicalmotion thereof without agglomeration. It will ensure the stability ofproduction.

The high-frequency induction plasma reactor is configured to preventplasma from being adsorbed to the inner wall of the reactor, therebymaximizing the manufacturing efficiency of plasma.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A plasma reactor apparatus for producing nano-powder comprising: anupper body having a reaction pipe receiving a reactor extendingvertically inside thereof, a high-frequency coil surrounding the outerperiphery of the reaction pipe, and a ceramic inner wall provided insidethe reaction pipe, the ceramic inner wall being formed with a pluralityof gas passing bores and defining gas movement passage with the reactionpipe therebetween for allowing the inflow of argon gas from the outsideinto the reactor; and a cover mounted to an upper end of the reactor andadapted to seal the reactor, the cover being provided with a powderinjection tube communicating with the reactor; wherein the upper body isprovided with a permanent magnet assembly around the periphery of thehigh-frequency coil, the magnet assembly comprising a plurality ofpermanent magnets uniformly spaced apart from one another and combinedby fixing means and having inner ends of the same polarity as oneanother disposed radially inwardly in contrast to opposite ends thereofbeing a different polarity and disposed radially outwardly so that theycompress plasma inside the reactor, thereby preventing the plasma frombeing adsorbed to the wall of the reactor.
 2. The plasma reactorapparatus for producing nano-powder as set forth in claim 1, wherein thereaction pipe comprises ceramic inner and outer side walls defining aspace therebetween, into which water is charged and circulated therein.3. The plasma reactor apparatus for producing nano-powder as set forthin claim 1, wherein the gas passing bores formed to penetrate throughthe inner wall are inclined so that an outlet of each gas passing boreis inclined laterally and downwardly from an inlet thereof, therebycreating a helical eddy current of inflow gas having passed through thegas passing bores within the reactor.
 4. The plasma reactor apparatusfor producing nano-powder as set forth in claim 1, wherein the upperbody is provided with a plurality of insulating bars mounted around itsouter periphery in order to protect the high-frequency coil and thereaction pipe.
 5. The plasma reactor apparatus for producing nano-powderas set forth in claim 1, wherein: the cover is provided with a gasinflow canal which communicates the powder injection tube for allowingthe inflow of gas from the outside; and the cover is also providedtherein with a cooling tube arranged adjacent to a lower surface of thecover, the cooling tube being adapted to receive cooling water from theoutside, thereby cooling the lower surface of the cover using thecooling water.
 6. The plasma reactor apparatus for producing nano-powderas set forth in claim 1, further comprising: a lower body mounted underthe upper body; wherein the lower body having a reaction pipe receivinga reactor communicating with the reactor of the upper body, ahigh-frequency coil surrounding the periphery of the reaction pipe, anda ceramic inner wall provided inside the reaction pipe, the reactor ofthe lower body having a diameter larger than that of the reactor of theupper body, the high frequency coil of the lower body having a capacitylarger than that of the high frequency coil of the upper body, theceramic inner wall being formed with a plurality of gas passing boresand defining a gas movement passage with the reaction pipe therebetweenfor allowing the inflow of argon gas from the outside into the reactor.7. The plasma reactor apparatus for producing nano-powder as set forthin claim 6, wherein the reaction pipe comprises ceramic inner and outerside walls defining a space therebetween, into which water is chargedand circulated therein.
 8. The plasma reactor apparatus for producingnano-powder as set forth in claim 6, wherein the gas passing boresformed to penetrate through the inner wall are inclined so that anoutlet of each gas passing bore is inclined laterally and downwardlyfrom an inlet thereof, thereby creating a helical eddy current of inflowgas having passed through the gas passing bores within the reactor. 9.The plasma reactor apparatus for producing nano-powder as set forth inclaim 1, wherein the lower body is provided with a permanent magnetassembly around the periphery of the high-frequency coil, the magnetassembly comprising a plurality of permanent magnets uniformly combinedby fixing means and having inner ends of the same polarity as oneanother so that they compress plasma inside the reactor, therebypreventing the plasma from being adsorbed to the wall of the reactor.10. The plasma reactor apparatus for producing nano-powder as set forthin claim 6, wherein the lower body is provided with a plurality ofinsulating bars mounted around its outer periphery in order to protectthe high-frequency coil and the reaction pipe.
 11. The plasma reactorapparatus for producing nano-powder as set forth in claim 6, wherein theupper body and lower body are formed with insulators between theiradjacent connecting ends facing each other, the insulators serving toprevent the conduction of heat toward the upper and lower bodies. 12.The plasma reactor apparatus for producing nano-powder as set forth inclaim 2, further comprising: a lower body mounted under the upper body;wherein the lower body having a reaction pipe receiving a reactorcommunicating with the reactor of the upper body, a high-frequency coilsurrounding the periphery of the reaction pipe, and a ceramic inner wallprovided inside the reaction pipe, the reactor of the lower body havinga diameter larger than that of the reactor of the upper body, the highfrequency coil of the lower body having a capacity larger than that ofthe high frequency coil of the upper body, the ceramic inner wall beingformed with a plurality of gas passing bores and defining a gas movementpassage with the reaction pipe therebetween for allowing the inflow ofargon gas from the outside into the reactor.
 13. The plasma reactorapparatus for producing nano-powder as set forth in claim 3, furthercomprising: a lower body mounted under the upper body; wherein the lowerbody having a reaction pipe receiving a reactor communicating with thereactor of the upper body, a high-frequency coil surrounding theperiphery of the reaction pipe, and a ceramic inner wall provided insidethe reaction pipe, the reactor of the lower body having a diameterlarger than that of the reactor of the upper body, the high frequencycoil of the lower body having a capacity larger than that of the highfrequency coil of the upper body, the ceramic inner wall being formedwith a plurality of gas passing bores and defining a gas movementpassage with the reaction pipe therebetween for allowing the inflow ofargon gas from the outside into the reactor.
 14. The plasma reactorapparatus for producing nano-powder as set forth in claim 1, furthercomprising: a lower body mounted under the upper body; wherein the lowerbody having a reaction pipe receiving a reactor communicating with thereactor of the upper body, a high-frequency coil surrounding theperiphery of the reaction pipe, and a ceramic inner wall provided insidethe reaction pipe, the reactor of the lower body having a diameterlarger than that of the reactor of the upper body, the high frequencycoil of the lower body having a capacity larger than that of the highfrequency coil of the upper body, the ceramic inner wall being formedwith a plurality of gas passing bores and defining a gas movementpassage with the reaction pipe therebetween for allowing the inflow ofargon gas from the outside into the reactor.
 15. The plasma reactorapparatus for producing nano-powder as set forth in claim 4, furthercomprising: a lower body mounted under the upper body; wherein the lowerbody having a reaction pipe receiving a reactor communicating with thereactor of the upper body, a high-frequency coil surrounding theperiphery of the reaction pipe, and a ceramic inner wall provided insidethe reaction pipe, the reactor of the lower body having a diameterlarger than that of the reactor of the upper body, the high frequencycoil of the lower body having a capacity larger than that of the highfrequency coil of the upper body, the ceramic inner wall being formedwith a plurality of gas passing bores and defining a gas movementpassage with the reaction pipe therebetween for allowing the inflow ofargon gas from the outside into the reactor.
 16. The plasma reactorapparatus for producing nano-powder as set forth in claim 5, furthercomprising: a lower body mounted under the upper body; wherein the lowerbody having a reaction pipe receiving a reactor communicating with thereactor of the upper body, a high-frequency coil surrounding theperiphery of the reaction pipe, and a ceramic inner wall provided insidethe reaction pipe, the reactor of the lower body having a diameterlarger than that of the reactor of the upper body, the high frequencycoil of the lower body having a capacity larger than that of the highfrequency coil of the upper body, the ceramic inner wall being formedwith a plurality of gas passing bores and defining a gas movementpassage with the reaction pipe therebetween for allowing the inflow ofargon gas from the outside into the reactor.